Blood culture bottles are frequently found to be positive before colonies of the infecting organism are available for susceptibility and biochemical testing. It is current practice to perform susceptibility testing and screening biochemical testing from positive blood culture bottles and then to repeat these from colonies. This repetition means increased material and labor costs for the laboratory, and has not been demonstrated to be necessary. This study will compare bottle and colony susceptibility and biochemical results to define the circumstances under which repeating the tests from colonies is really necessary.